Evaluation of Differences in Patellar Height After Patellar Stabilization Procedures Not Intended to Address Patella Alta: A Multicenter Study.

Background: Recent studies have reported conflicting results as to whether isolated medial patellofemoral ligament reconstruction (MPFLr) leads to decreased patellar height.

Purpose: To investigate if patellar stabilization surgery not intended to address patella alta influences patellar height.

Study Design: Cohort study; Level of evidence, 3.

A modified Delphi consensus statement on patellar instability: part I.

Aims: The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach.

Methods: A total of 60 surgeons from 11 countries were invited to develop consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest within patellar instability.

A modified Delphi consensus statement on patellar instability: part II.

Aims: The aim of this study was to establish consensus statements on medial patellofemoral ligament (MPFL) reconstruction, anteromedialization tibial tubercle osteotomy, trochleoplasty, and rehabilitation and return to sporting activity in patients with patellar instability, using the modified Delphi process.

Methods: This was the second part of a study dealing with these aspects of management in these patients. As in part I, a total of 60 surgeons from 11 countries contributed to the development of consensus statements based on their expertise in this area.

Adding Tibial Tuberosity Medialization to Medial Patellofemoral Ligament Reconstruction Reduces Lateral Patellar Maltracking During Multidirectional Motion in a Computational Simulation Model.

Purpose: To determine whether adding tibial tuberosity medialization to medial patellofemoral ligament (MPFL) reconstruction reduces lateral patellar maltracking during a dynamic multidirectional activity and to investigate when medial patellofemoral contact pressures are elevated during daily activities, such as squatting.

Methods: Seven computational models representing knees with patellar instability, including lateral patellar maltracking, were evaluated following simulated MPFL reconstruction (bisect offset index > .75).

How Mental Health Affects Injury Risk and Outcomes in Athletes.

Context: The importance of mental health among athletes is becoming more recognized and valued. Athletes experience symptoms of depression, anxiety, and related mental health disorders at rates similar to those of the general population, but because athletes face unique cultural and environmental pressures, such disorders are exacerbated in the context of an injury. Furthermore, we review the less well-known evidence that mental health disorders in athletes are associated with an increased risk of injury.

Evaluating Patellofemoral Patients: Physical Examination, Radiographic Imaging, and Measurements.

Patellofemoral pain is one of the most common symptoms of patients presenting to sports medicine clinics. Obtaining a pertinent history and performing a thorough examination is crucial to identifying the subset of patients with instability who are most likely to benefit from surgical stabilization. A comprehensive radiographic work-up that includes standard radiographs and advanced imaging helps elucidate the diagnosis and provides crucial information for preoperative planning.

Influence of tibial tuberosity position and trochlear depth on patellar tracking in patellar instability: Variations with Patella Alta.

Background: Patella alta reduces articular constraints acting on the patella from the trochlear groove with the knee extended. The current study was performed to address how patella alta alters the influence of tibial tuberosity position and trochlear depth on patellar tracking in patients being treated for patellar instability.

Methods: Fifteen subjects with recurrent patellar instability participated in knee extension within a dynamic CT scanner.

Noniatrogenic Medial Patellar Dislocations: Case Series and International Patellofemoral Study Group Experience.

Background: Most patellar dislocations occur in a lateral direction because of a summed lateral force vector and predisposing anatomic risk factors. Medial patellar instability is rare and is a well-recognized iatrogenic complication of an overly aggressive lateral retinacular release. Noniatrogenic medial patellar dislocations are rare.

Tibial tuberosity anteriomedialization vs. medial patellofemoral ligament reconstruction for treatment of patellar instability related to malalignment: Computational simulation.

Background: Medial patellofemoral ligament reconstruction and tibial tuberosity anteromedialization are common treatment options for recurrent lateral patellar instability, although ligament reconstruction is not commonly applied to knees with lateral malalignment.

Methods: Multibody dynamic simulation was used to assess knee function following tibial tuberosity anteromedialization and medial patellofemoral ligament reconstruction for knees with lateral malalignment. Dual limb squatting was simulated with six models representing knees being treated for patellar instability with an elevated tibial tuberosity to trochlear groove distance.

Factors Influencing Graft Function following MPFL Reconstruction: A Dynamic Simulation Study.

Medial patellofemoral ligament (MPFL) reconstruction is currently the primary surgical procedure for treating recurrent lateral patellar instability. The understanding of graft function has largely been based on studies performed with normal knees. The current study was performed to characterize graft function following MPFL reconstruction, focusing on the influence of pathologic anatomy on graft tension, variations with knee flexion, and the influence on patellar tracking.

Accuracy and Reliability of the Visual Assessment of Patellar Tracking.

Background: Abnormal patellar tracking is described as a "J-sign" when the patella exhibits excessive lateral displacement during active knee extension.

Purpose: To determine (1) the accuracy and reliability of the visual assessment of patellar tracking when viewed by surgeons with patellofemoral expertise and (2) whether surgeon experience (in years) correlates with the ability to accurately identify the presence and severity of patellar maltracking.

Study Design: Cohort study (diagnosis); Level of evidence, 2.

Anteroposterior distance between the tibial tuberosity and trochlear groove in patients with patellar instability.

Background: Our objective was to describe a measurement to assess sagittal tibial tuberosity (TT)-trochlear groove (TG) distance and to compare this between asymptomatic (control) patients and patients with symptomatic patellar instability.

Methods: We compared static CT images of 22 fully extended knees of patients with symptomatic patellar instability with images of 22 asymptomatic knees. TT-TG distance was measured to quantify lateralization of the TT, and anteroposterior TT-TG distance was used to quantify the sagittal distance between these two points.

A Primer on Running for the Orthopaedic Surgeon.

Long-distance running has become increasingly popular during the past decades. Many running patients pose questions to their orthopaedic surgeons regarding risks, benefits, and running techniques. This article identifies 11 running-related questions that patients may ask and provides information to help answer those questions.

The Evolution of Patellofemoral Instability Surgery During the Past 25 Years.

Surgical treatment of patellofemoral instability has evolved during the past 25 years as we developed a better appreciation of anatomy and a more sophisticated understanding of pathophysiology. Currently, most patellofemoral surgeons use soft tissue procedures like medial patellofemoral ligament reconstruction to treat medial soft tissue insufficiency and tibial tuberosity or femoral osteotomy to correct substantial bony malalignment. Advances in imaging technology and computational analysis have allowed for more precise preoperative planning and outcome modeling so that the optimum operation using ≥1 of these procedures can be designed to meet the unique needs of an individual patient.

Complications After Tibial Tuberosity Osteotomy: Association With Screw Size and Concomitant Distalization.

Background: Tibial tuberosity osteotomy (TTO) is a versatile procedure commonly used to treat patellar instability as well as to unload cartilage lesions. TTO with concomitant distalization (TTO-d) may be performed in patients with patella alta to stabilize the patella by helping it to engage in the trochlea earlier during flexion.

Purpose: To identify and compare perioperative complications in patients who underwent TTO and those who underwent TTO-d and to analyze risk factors associated with these complications.

Computational simulation of medial versus anteromedial tibial tuberosity transfer for patellar instability.

The study utilizes dynamic simulation of knee function to determine how tibial tuberosity medialization and anteromedialization influence patellar tracking and contact pressures for knees with patellar instability. Dual limb squatting was simulated with six multibody dynamic simulation models representing knees being treated for patellar instability. Each knee exhibited lateral patellar maltracking in the pre-operative condition based on the bisect offset index.

Tibial tuberosity to trochlear groove distance and its association with patellofemoral osteoarthritis-related structural damage worsening: data from the osteoarthritis initiative.

Objectives: To determine whether the tibial tuberosity-to-trochlear groove (TT-TG) distance is associated with concurrent patellofemoral joint osteoarthritis (OA)-related structural damage and its worsening on 24-month follow-up magnetic resonance imaging (MRI) in participants in the Osteoarthritis Initiative (OAI).

Methods: Six hundred subjects (one index knee per participant) were assessed. To evaluate patellofemoral OA-related structural damage, baseline and 24-month semiquantitative MRI Osteoarthritis Knee Score (MOAKS) variables for cartilage defects, bone marrow lesions (BMLs), osteophytes, effusion, and synovitis were extracted from available readings.

Dynamic tracking influenced by anatomy following medial patellofemoral ligament reconstruction: Computational simulation.

Background: Continued patellar instability can occur following medial patellofemoral ligament (MPFL) reconstruction. Computational simulation of function was used to investigate the influence of the lateral position of the tibial tuberosity, trochlear dysplasia and patella alta on lateral patellar tracking following MPFL reconstruction.

Methods: Multibody dynamic simulation models were developed to represent nine knees being treated for recurrent patellar instability.

Allowing one quadrant of patellar lateral translation during medial patellofemoral ligament reconstruction successfully limits maltracking without overconstraining the patella.

Purpose: Graft tensioning during medial patellofemoral ligament (MPFL) reconstruction typically allows for lateral patellar translation within the trochlear groove. Computational simulation was performed to relate the allowed patellar translation to patellofemoral kinematics and contact pressures.

Methods: Multibody dynamic simulation models were developed to represent nine knees with patellar instability.

Editorial Commentary: Measuring Coronal (Mal)Alignment for Patients With Patellar Instability: Tibial Tubercle-to-Trochlear Groove Versus Tibial Tubercle-to-Posterior Cruciate Ligament Distance.

Excessive lateralization of the tibial tuberosity is one of the anatomic factors that contribute to lateral patellar instability, which we usually correct surgically with tibial tuberosity osteotomy. Traditionally, coronal alignment was determined clinically by measuring the Q angle, which has proven to be unreliable. Radiographic measurements of coronal alignment made using computed tomography and magnetic resonance imaging are more reliable and have become the standard for determining the need for corrective tibial tuberosity osteotomy.

Measuring Malalignment on Imaging in the Treatment of Patellofemoral Instability.

Assessment of malalignment is an important factor in determining surgical treatment options for patellar instability. Measurement of tibial tubercle-trochlear groove (TT-TG) distance is valuable in planning surgical treatment for patellar instability, because it quantifies a component of malalignment and aids in deciding whether to perform tibial tuberosity osteotomy. In this paper we review how TT-TG distance should be understood in the context of many measurement factors to allow for an individualized procedure that addresses the specific contributors to patellar instability in each patient.

Rehabilitation After Medial Patellofemoral Ligament Reconstruction.

Patellar instability resulting from subluxation or dislocation is a painful and commonly recurring condition. Retinacular restraints control patellar tracking, limiting the movement of the patella in the trochlear groove. The medial patellofemoral ligament (MPFL) is considered the main soft tissue stabilizer against lateral displacement.

Complications of Tibial Tuberosity Osteotomy.

It is important to understand potential complications of tibial tuberosity osteotomies (TTOs) and how to avoid them. TTO is associated with a 1% to 3% rate of tibial fracture and 1% rate of nonunion. Early weight-bearing and complete detachment of the distal tuberosity may increase these risks.

When and How Far to Move the Tibial Tuberosity in Patients With Patellar Instability.

The many factors contributing to patellar instability have led to various surgical techniques that are used commonly today. When surgery is deemed necessary, the operation should be tailored to the patient's specific pathoanatomy. Patients with malalignment can often be stabilized by moving the tibial tuberosity to a more medial, anteromedial, or distal position.